1. Field of the Invention
The invention relates to an appliance or terminal such as an audio reader appliance that is designed to be connected to one or more external loudspeakers in order to play back an audio source via the external loudspeakers.
2. Brief Discussion of the Related Art
Numerous portable appliances enable a wide variety of audio sources to be received and listened to, which sources come from a variety of origins: radio, telephone, television, recorded music, etc.
Given the small dimensions of such portable appliances, it is not possible to fit them with means that enable them to play back a high quality sound signal. In particular, the space available for loudspeakers is small, so the audio power and passband are necessarily limited on such appliances.
That is why it is known to provide a docking station that is fitted with additional loudspeakers for improving the sound rendering of the sound source read by the portable appliance, which docking station is generally fixed.
Specifically, the user merely engages the portable appliance in the docking station, with those two elements being provided with complementary electric connectors, thereby automatically causing the audio source to be played back via the additional loudspeakers fitted to the docking station.
In patent EP 1 564 561, proposals are made to detect the presence of additional loudspeakers by measuring the variation in the power supply current of the amplifier incorporated in the portable appliance that delivers the signal to the additional loudspeakers.
Nevertheless, that solution is found to be relatively expensive to implement in order to obtain detection of sufficient reliability: it requires the power supply current to be characterized and stored in the appliance, and it also requires current measuring means of relatively high accuracy.